Screen Space Reflections in EEVEE
I haven't dig into the theory of the implementation yet, but I have a feeling that Screen Space Reflection is just mirroring the already rendered pixel (aka what you actually see on the screen, the screen space data).

I think that's the intended behaviour. It's an heavy approximation that on the other hand gives nice and fast results, expecially for the objects that touch the ground.

You'll have to use a Reflection Plane to get the reflections of the occluded geometries.